A high-nitrogen single-phase multi-principal-element alloy and a preparation method thereof

Abstract

The application provides a high-nitrogen single-phase multi-main-element alloy and a preparation method thereof, and belongs to the technical field of metal materials.The high-nitrogen single-phase multi-main-element alloy provided by the application comprises the following elements in percentage by mass: Fe: 25-35%, Mn: 15-25%, Co: 15-25%, Cr: 15-25%, Ni: 3-10%, and N: 0.5-3.5%.The tensile strength of the high-nitrogen single-phase multi-main-element alloy provided by the application is 740 MPa, which is increased by nearly 300 MPa compared with the alloy without adding N element, and meanwhile, the plasticity of the alloy is increased from 45% to 75% after adding N, so that the strength and plasticity are simultaneously improved.In addition, the high-nitrogen single-phase multi-main-element alloy provided by the application does not need to add rare earth elements and other noble metal elements, and does not need to rely on complex production processes and special equipment, so that the production cost is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal materials, in particular to a high-nitrogen single-phase multi-principal-element alloy and a preparation method thereof. BACKGROUND

[0002] With the development of science and technology, the development of advanced metal materials suitable for extreme service conditions has been raised to a strategic level. Due to the limitation of single principal element, the space for alloy development of traditional metal materials is limited, so it is urgent to expand the design space of new alloys. However, the strength and plasticity of alloys in metal materials have always been a pair of contradictions, and how to simultaneously improve the strength and plasticity of alloys to cope with safe and reliable service performance remains to be studied. The main single-phase multi-principal-element alloys in the prior art cannot meet the application requirements in terms of strength and plasticity, and the dual-phase or multi-phase multi-principal-element alloys are usually accompanied by problems such as complex alloy composition, unstable second phase, and difficult-to-control process. Therefore, how to prepare a high-performance multi-principal-element alloy under the premise of maintaining a single phase has become a key problem to be solved.

[0003] At present, adding an appropriate amount of interstitial elements to increase lattice distortion and achieve interstitial solid solution strengthening is one of the effective means for preparing high-performance single-phase multi-principal-element alloys. The invention patent CN201910924373.0 introduces a high-nitrogen high-entropy alloy and a preparation method thereof, which realizes the synergistic effect of austenite and nano precipitates under room temperature environment by adding 2.0-4.0 mole percent of nitrogen element and adjusting Fe, Co, Mn and Cr elements. Although the strength of the alloy reaches 1.3 GPa, the elongation is only 20%, and the nano-scale precipitates also have the problem of insufficient thermal stability, which tests the stability of the material performance to a certain extent. The invention patent CN201710583007.4 introduces a scheme of introducing a certain content of carbon element into the Fe40Mn40Co10Cr10 alloy to form interstitial solid solution and carbide with the matrix. The alloy prepared by this method not only sacrifices the plasticity of the alloy when improving the strength of the alloy, but also still needs to rely on complex preparation steps to further regulate the organization to ensure the single-phase structure, which increases energy consumption and process cost.

[0004] Therefore, it is urgent to provide a single-phase multi-principal-element alloy which can have high strength and plasticity at the same time. SUMMARY

[0005] The purpose of the present application is to provide a high-nitrogen single-phase multi-principal-element alloy and a preparation method thereof. The high-nitrogen single-phase multi-principal-element alloy provided by the present application has high strength and plasticity at the same time.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The application provides a high-nitrogen single-phase multi-principal-element alloy, which comprises the following elements in percentage by mass: Fe: 25-35%, Mn: 15-25%, Co: 15-25%, Cr: 15-25%, Ni: 3-10% and N: 0.5-3.5%.

[0008] Preferably, the high-nitrogen single-phase multi-principal-element alloy comprises the following elements in percentage by mass: Fe: 26-34%, Mn: 16-24%, Co: 16-24%, Cr: 16-24%, Ni: 4-9% and N: 0.8-3%.

[0009] Preferably, the high-nitrogen single-phase multi-principal-element alloy comprises the following elements in percentage by mass: Fe: 27-33%, Mn: 17-23%, Co: 17-23%, Cr: 17-23%, Ni: 5-8% and N: 1-2.5%.

[0010] The application further provides a preparation method of the high-nitrogen single-phase multi-principal-element alloy.

[0011] (1) sequentially melting and casting alloy raw materials to obtain an alloy ingot;

[0012] (2) sequentially performing hot rolling and solid solution treatment on the alloy ingot obtained in the step (1) to obtain the high-nitrogen single-phase multi-principal-element alloy.

[0013] Preferably, the melting in the step (1) is performed for 3-6 times.

[0014] Preferably, the cooling mode of the casting in the step (1) is circulating water cooling, and the temperature of the circulating water is 25 DEG C.

[0015] Preferably, the hot rolling in the step (2) is performed at a starting rolling temperature of 900-950 DEG C and a final rolling temperature of 850-950 DEG C.

[0016] Preferably, the hot rolling in the step (2) is performed for 4-8 times, the total rolling reduction is 45-55%, and the rolling reduction of each pass is 5-10%.

[0017] Preferably, the solid solution treatment in the step (2) is performed at a holding temperature of 1100-1250 DEG C for 2-4 h.

[0018] Preferably, the cooling mode of the solid solution treatment in the step (2) is water cooling to room temperature.

[0019] The application provides a high-nitrogen single-phase multi-principal-element alloy, which comprises the following elements in percentage by mass: Fe: 25-35%, Mn: 15-25%, Co: 15-25%, Cr: 15-25%, Ni: 3-10% and N: 0.5-3.5%.

[0020] The results of the embodiment show that the tensile strength of the high-nitrogen single-phase multi-principal-element alloy provided by the application is 740 MPa, which is increased by nearly 300 MPa compared with the alloy without adding N element, and the plasticity of the alloy after adding N is increased from 45% to 75%, so that the strength and plasticity are simultaneously improved.

[0021] In addition, the high-nitrogen single-phase multi-principal-element alloy provided by the application does not need to add rare earth and other noble metals, and does not need to rely on complex production processes and special equipment, so that the production cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Fig. 1 is a scanning electron microscope secondary electron image of the high-nitrogen single-phase multi-principal-element alloy of the embodiment 1 of the application;

[0023] Figure 2 Fig. 3 is an XRD spectrum of the high-nitrogen single-phase multi-principal-element alloy of the embodiment 1 of the application;

[0024] Figure 3 Fig. 4 is a stress-strain curve of the high-nitrogen single-phase multi-principal-element alloy (N-added alloy) of the embodiment 1 of the application and the non-N-added alloy of the comparative example 1. DETAILED DESCRIPTION

[0025] The application provides a high-nitrogen single-phase multi-principal-element alloy, which comprises the following elements in percentage by mass: Fe: 25-35%, Mn: 15-25%, Co: 15-25%, Cr: 15-25%, Ni: 3-10% and N: 0.5-3.5%.

[0026] The high-nitrogen single-phase multi-principal-element alloy provided by the present application includes Fe: 25-35%, preferably 26-34%, more preferably 27-33%, and most preferably 28-32% by mass. By adding Fe element and controlling its content within the above range, the present application can form a single-phase austenite structure with Fe, Mn, Co, Cr and Ni, and has an FCC structure, which is beneficial to the alloy to obtain higher strength and plasticity.

[0027] The high-nitrogen single-phase multi-principal-element alloy provided by the present application includes Mn: 15-25%, preferably 16-24%, more preferably 17-23%, and most preferably 18-22% by mass. By adding Mn element and controlling its content within the above range, the present application can form a single-phase austenite structure with Fe, Co, Cr and Ni, and has an FCC structure, which is beneficial to the alloy to obtain higher strength and plasticity.

[0028] The high-nitrogen single-phase multi-principal-element alloy provided by the present application includes Co: 15-25%, preferably 16-24%, more preferably 17-23%, and most preferably 18-22% by mass. By adding Co element and controlling its content within the above range, the present application can form a single-phase austenite structure with Fe, Mn, Cr and Ni, and has an FCC structure, which is beneficial to the alloy to obtain higher strength and plasticity.

[0029] The high-nitrogen single-phase multi-principal-element alloy provided by the present application includes Cr: 15-25%, preferably 16-24%, more preferably 17-23%, and most preferably 18-22% by mass. By adding Cr element and controlling its content within the above range, the present application can form a single-phase austenite structure with Fe, Mn, Co and Ni, and has an FCC structure, which is beneficial to the alloy to obtain higher strength and plasticity.

[0030] The high-nitrogen single-phase multi-principal-element alloy provided by the present application includes Ni: 3-10%, preferably 4-9%, more preferably 5-8%, and most preferably 6-7% by mass. By adding Ni element and controlling its content within the above range, the present application can form a single-phase austenite structure with Fe, Mn, Co and Cr, and has an FCC structure, which is beneficial to the alloy to obtain higher strength and plasticity.

[0031] The high-nitrogen single-phase multi-principal alloy provided by this invention comprises N: 0.5-3.5%, preferably 0.8-3%, more preferably 1-2.5%, and most preferably 1-2%, by mass percentage. By adding Ni, this invention can utilize its interstitial strength to improve the alloy's strength and plasticity. Furthermore, the addition of a high Ni content facilitates lattice distortion in the alloy, increasing dislocation movement resistance and simultaneously increasing the stacking fault energy of part of the matrix, which is beneficial for stabilizing the FCC structure, thereby effectively improving the alloy's strength and plasticity. In addition, Ni dissolved in the multi-principal matrix can locally form Ni atom clusters or form short-range ordered structures with other alloying elements. High-density coherent nanoclusters are more conducive to improving the alloy's resistance to deformation, providing obstacles to dislocation movement while ensuring single-phase properties, thereby further improving the alloy's strength and plasticity.

[0032] The high-nitrogen single-phase multi-principal-element alloy provided by this invention has both high strength and plasticity, and does not require the addition of rare earth elements or other precious metals, nor does it rely on complex production processes and special equipment, resulting in low production costs.

[0033] This invention also provides a method for preparing the high-nitrogen single-phase multi-principal-element alloy described above, comprising the following steps:

[0034] (1) The alloy raw materials are melted and cast sequentially to obtain alloy ingots;

[0035] (2) The alloy ingot obtained in step (1) is subjected to hot rolling and solution treatment in sequence to obtain a high-nitrogen single-phase multi-principal-element alloy.

[0036] This invention involves sequentially melting and casting alloy raw materials to obtain alloy ingots.

[0037] In this invention, the alloy raw materials preferably include iron particles, nickel particles, manganese particles, chromium particles, cobalt particles, and chromium nitride particles. This invention does not have special requirements regarding the source of the alloy raw materials; they can be prepared using methods well-known in the art or be commercially available materials.

[0038] In this invention, the number of melting cycles is preferably 3 to 6. By controlling the number of melting cycles within the above range, this invention ensures that the various alloying elements in the molten alloy are mixed evenly, which is more conducive to obtaining an alloy ingot with a uniform microstructure.

[0039] In this invention, the melting equipment is preferably an ultra-high vacuum argon-protected induction furnace. By using an ultra-high vacuum argon-protected induction furnace for melting, this invention can avoid the oxidation and burning loss of various alloying elements in the alloy raw materials and the introduction of impurities, while ensuring that nitrogen in nitrogen-containing raw materials can exist stably in the alloy liquid, which is more conducive to obtaining high-nitrogen single-phase multi-principal element alloys with high target alloying element content.

[0040] In the present application, the cooling mode of the casting is preferably circulating water cooling, and the temperature of the circulating water is preferably 25℃. By controlling the parameters of the casting within the above range, the present application can reduce the ingot structure defects and ensure the uniformity of the ingot structure.

[0041] In the present application, the mold of the casting is preferably a copper mold. By selecting the copper mold for casting, the present application can rapidly cool the alloy liquid, which is more conducive to obtaining an ingot with fine grains.

[0042] After obtaining the alloy ingot, the present application sequentially performs hot rolling and solid solution treatment on the obtained alloy ingot to obtain a high-nitrogen single-phase multi-principal-element alloy.

[0043] In the present application, the opening rolling temperature of the hot rolling is preferably 900-950℃, and the final rolling temperature of the hot rolling is preferably 850-950℃. By controlling the temperature of the hot rolling within the above range, the present application can reduce the deformation resistance of the ingot, improve the plasticity of the ingot, and more favorably improve the strength and plasticity of the alloy by dislocation accumulation.

[0044] In the present application, the number of times of the hot rolling is preferably 4-8 times, the total reduction of the hot rolling is preferably 45-55%, more preferably 48-52%, and the reduction of each pass of the hot rolling is preferably 5-10%, more preferably 6-9%. By controlling the deformation parameters of the hot rolling within the above range, the present application can effectively break coarse dendrites, promote recrystallization, refine grains, and make the element distribution and structure more uniform, which is more conducive to improving the strength and plasticity of the alloy.

[0045] In the present application, the cooling mode of the hot rolling is preferably natural cooling to room temperature.

[0046] In the present application, the holding temperature of the solid solution treatment is preferably 1100-1250℃, more preferably 1150-1200℃, and the holding time of the solid solution treatment is preferably 2-4h, more preferably 2.5-3.5h. By performing the solid solution treatment and controlling the parameters of the solid solution treatment within the above range, the present application can make the precipitated phase resolute in the matrix, improve the strength and plasticity of the alloy by solid solution strengthening of each alloy element.

[0047] In the present application, the cooling mode of the solid solution treatment is preferably water cooling to room temperature. By adopting the cooling mode of water cooling to room temperature, the present application can rapidly reduce the temperature of the solid solution treatment to room temperature, ensure that the grains will not grow under the action of residual heat and avoid the precipitation of alloy elements, thereby obtaining a solid solution structure, which is more conducive to the alloy maintaining single-phase.

[0048] The preparation method provided by the present application can obtain a high-nitrogen single-phase multi-principal-element alloy with improved strength and plasticity, and the operation is simple, the parameters are easy to control, special equipment is not required, and the production cost is low.

[0049] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0050] Embodiment 1

[0051] A high-nitrogen single-phase multi-principal-element alloy, which is composed of the following elements with mass percentages: Fe: 31.62%, Mn: 20.7%, Co: 19.76%, Cr: 19.76%, Ni: 6.9%, and N: 1.2%.

[0052] The preparation method of the high-nitrogen single-phase multi-principal-element alloy comprises the following steps:

[0053] (1) sequentially melting and casting alloy raw materials to obtain an alloy ingot;

[0054] Specifically, the alloy raw materials of iron particles, nickel particles, manganese particles, chromium particles, cobalt particles, and chromium nitride particles are placed in an ultra-high vacuum argon protection induction furnace for 6 times of melting to obtain alloy liquid; then, the alloy liquid is cast into a copper mold under the condition of circulating water at 25℃, and after the riser is removed, an alloy ingot with a size of 5510mm 3 (thickness of 10mm) is obtained.

[0055] (2) sequentially hot-rolling and solid solution treating the alloy ingot obtained in the step (1) to obtain a high-nitrogen single-phase multi-principal-element alloy;

[0056] Specifically, the alloy ingot is heated for 0.5h to reach a hot-rolling temperature of 900℃, the final rolling temperature is 850℃, the hot-rolling pass is 5 times, the rolling reduction of each pass is 10%, the total rolling reduction is 50%, and the ingot blank with a thickness of 5mm is obtained after natural cooling to room temperature; then, solid solution treatment is performed, the holding temperature of the solid solution treatment is 1200℃, the holding time of the solid solution treatment is 2h, and then the high-nitrogen single-phase multi-principal-element alloy is obtained after water cooling to room temperature.

[0057] Comparative Example 1

[0058] A single-phase multi-principal-element alloy without nitrogen (N-free alloy), which is composed of the following elements with mass percentages: Fe: 32.6%, Mn: 20.7%, Co: 19.86%, Cr: 19.86%, and Ni: 6.98%.

[0059] The preparation method of the single-phase multi-principal-element alloy without nitrogen comprises the following steps:

[0060] (1) sequentially melting and casting alloy raw materials to obtain an alloy ingot;

[0061] Specifically: Iron, nickel, manganese, chromium, and cobalt particles, the alloy raw materials, are placed in an ultra-high vacuum argon-protected induction furnace and smelted six times to obtain a liquid alloy; then, under circulating water conditions at 25°C, it is cast into a copper mold, and after removing the riser, a molten alloy with a size of 5510 mm is obtained. 3 Alloy ingots (10mm thick).

[0062] (2) The alloy ingot obtained in step (1) is subjected to hot rolling and solution treatment in sequence to obtain a nitrogen-free single-phase multi-principal-element alloy;

[0063] Specifically: The alloy ingot is heated for 0.5 hours to reach the initial rolling temperature of 900℃ for hot rolling, and the final rolling temperature is 850℃. The hot rolling is performed in 5 passes, with a reduction of 10% per pass and a total reduction of 50%. After natural cooling to room temperature, an ingot with a thickness of 5mm is obtained. Then, a solution treatment is performed at a holding temperature of 1200℃ for 2 hours. After water cooling to room temperature, a high-nitrogen single-phase multi-principal-element alloy is obtained.

[0064] The microstructure of the high-nitrogen single-phase multi-principal-element alloy of Example 1 was observed using scanning electron microscopy (SEM). The secondary electron micrographs obtained are shown below. Figure 1 As shown.

[0065] Depend on Figure 1 It can be seen that the high-nitrogen single-phase multi-principal-element alloy provided by the present invention has a uniform microstructure (the dark dots are unavoidable impurities), and a large number of annealed twins are visible, while maintaining the single-phase FCC structure.

[0066] Phase analysis of the high-nitrogen single-phase multi-principal-element alloy of Example 1 was performed using X-ray diffraction. The obtained XRD pattern is shown below. Figure 2 As shown.

[0067] Depend on Figure 2 It can be seen that the high-nitrogen single-phase multi-principal alloy (N-added alloy) provided by the present invention is an FCC phase and no other phases are formed, proving that the high-nitrogen single-phase multi-principal alloy of the present invention is a single phase.

[0068] According to the national standard GB / T228—2002 for room temperature tensile testing of metallic materials, the alloys provided in Example 1 and Comparative Example 1 were subjected to room temperature tensile tests. The stress-strain curves obtained from the tests are shown below. Figure 3 As shown.

[0069] Depend on Figure 3 It can be seen that the high-nitrogen single-phase multi-principal-element alloy (N-added alloy) provided by the present invention has a tensile strength of 740 MPa, which is nearly 300 MPa higher than that of the alloy without N in Comparative Example 1. At the same time, the alloy plasticity increased from 45% to 75% after adding N, achieving a simultaneous improvement in strength and plasticity.

[0070] In conclusion, the high-nitrogen single-phase multi-principal-element alloy has single-phase FCC structure, and has higher strength and plasticity, and has better application prospect.

[0071] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A high-nitrogen single-phase multi-principal element alloy, characterized by, Comprise the following mass percentage of elements: Fe: 26~34%, Mn: 16~24%, Co: 16~24%, Cr: 16~24%, Ni: 4~9% and N: 0.8~3%.

2. The high-nitrogen single-phase multi-principal element alloy of claim 1, wherein, Comprise the following mass percentage of elements: Fe: 27~33%, Mn: 17~23%, Co: 17~23%, Cr: 17~23%, Ni: 5~8% and N: 1~2.5%.

3. The method of producing high-nitrogen single-phase multi-principal element alloy according to any one of claims 1 to 2, characterized by, Comprise the following steps: (1) sequentially melt and cast alloy raw materials to obtain alloy ingot; (2) sequentially hot-rolling and solid solution treating the alloy ingot obtained in step (1) to obtain high-nitrogen single-phase multi-principal-element alloy.

4. The production method according to claim 3, wherein The number of melting in step (1) is 3~6 times.

5. The production method according to claim 3, wherein The cooling mode of casting in step (1) is circulating water cooling, and the temperature of the circulating water is 25℃.

6. The production method according to claim 3, wherein The opening rolling temperature of hot-rolling in step (2) is 900~950℃, and the final rolling temperature of hot-rolling is 850~950℃.

7. The production method according to claim 3 or 6, wherein The number of hot-rolling in step (2) is 4~8 times, the total reduction of hot-rolling is 45~55%, and the reduction of each pass of hot-rolling is 5~10%.

8. The production method according to claim 3, wherein The holding temperature of solid solution treatment in step (2) is 1100~1250℃, and the holding time of solid solution treatment is 2~4h.

9. The production method according to claim 3 or 8, characterized by, The cooling mode of solid solution treatment in step (2) is water cooling to room temperature.

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